1. Technical Field
The present invention generally relates to a cooling system capable of thermal insulation between a temperature control target and a fixing device and cooling of the temperature control target thermally insulated from the fixing device; and further to an image forming apparatus, such as a copier, a printer, a facsimile machine, a plotter, or a multifunction peripheral (MFP) including at least two of coping, printing, facsimile transmission, plotting, and scanning capabilities, that incorporates the cooling system.
2. Description of the Background Art
Electrophotographic image forming apparatuses, such as, printers, copiers, facsimile machines, plotters, or multifunction machines typically include various components (hereinafter “temperature control targets”) to be kept under predetermined reference temperature. Examples of temperature control targets include an image forming unit including a photoreceptor and a developing device, a reading device, an exposure device, and various types of motors. There are two factors to cause temperature rise of these components, namely, self-heating by driving or rotation thereof and thermal effects from separate heat sources.
Generally, the fixing device reaches a highest temperature inside the image forming apparatus and thus accounts for a major portion of the separate heat sources to affect the temperature rise of the temperature control target. Therefore, there are image forming apparatuses in which the fixing device is thermally insulated from an adjacent temperature control target. Other temperature control targets may be cooled locally as required.
For example, JP-2004-109356-A proposes thermally insulating the fixing device from the temperature control target.
In this configuration, an insulating member is provided between the fixing device and the temperature control target such as the image forming unit disposed above the fixing device, and heat of the fixing device is transmitted via air to the temperature control target to inhibit the temperature rise of the temperature control target.
Specifically, a planar heat pipe is provided between the temperature control target and the fixing device, and a heatsink provided at one end of the heat pipe is disposed inside an air duct for air suction and exhaust that parallels rotation shafts of a fixing roller and a pressure roller of the fixing device. An air suction fan is provided at one end of the air duct, and air introduced by the air suction fan into the air duct is directed to the heatsink. Heat absorbed by the planar heat pipe from the other end of the air duct is exhausted outside the apparatus.
Thermal insulation is thus provided between the temperature control target and the fixing device to prevent the temperature control target, which is positioned on the opposite side of the fixing device via the insulating member, from being heated by the heat from the fixing device.